1. Field of the Invention
The present invention pertains to digital image management. More particularly, this invention relates to a digital image management system that automatically extracts content information from digital images and associates the content information with the digital images such that the digital images can be effectively and efficiently searched and retrieved.
2. Description of the Related Art
As is known, photographic prints have traditionally been used for visual presentation. The photographic prints are desirable because photographic papers are relatively inexpensive and easily portable. However, when a viewer needs to locate a desired photographic picture among a large number of pictures, the viewer has to individually view each of the pictures until the desired picture is identified. This is typically a very time consuming process. The process can also be very frustrating especially when the desired picture needs to be identified quickly.
In order to reduce the time one needs to find the desired picture among a large number of pictures, the pictures can be organized into a number of different categories. The organization typically involves labeling containers that store the pictures and building index lookup tables so that the viewer can locate the appropriate container or containers for the desired category relatively quickly. The disadvantage of this prior art approach is that a lot of time is typically spent on categorizing the pictures and arranging them according their categories. Moreover, even with this approach, the task of searching for the desired picture is still time consuming and difficult. The viewer needs to remember which picture belongs to which category in order to find the desired picture. The viewer also needs to go through the pictures within the desired category in order to identify the desired picture. Furthermore, each picture is assigned to one category.
In addition, this prior art image management system may not function properly if pictures are misplaced or mis-categorized. When this occurs, the desired picture may not be identified unless all or most of the pictures have been viewed. In this case, more time is needed to find the desired picture.
With the advance of computer technologies, it is now possible to store an image in a computer system. This can be done using a scanner that converts the image on a print or film into a digital image. The digital image includes image pixels (or dots) arranged in a matrix. The data for each image pixel are then stored in the computer. The digital image can be retrieved for display from the computer. The digital image can also be digitally altered in the computer. Moreover, the digital image can be transmitted to a remote computer for viewing via a communication network. This allows real time viewing of the image.
However, searches of these digital images based on their image contents in the computer are still nearly impossible. In order to identify a desired image stored in the computer, the computer can only compare the image pixel data of an input image with the corresponding pixel data of each of the images stored in the computer. The comparison typically takes a very long time to complete and uses a lot of system resources (e.g., memory and communication bandwidth). This is because the computer has to compare each image pixel data of the input image with the corresponding image pixel data of each of the stored images. A match occurs when each pixel data of the input image is similar the corresponding pixel data of a stored image. Using this method, unless the two compared images are very similar, it is very difficult to find a match between any two images. This is especially true because noise and other positional errors may be introduced into the image data during scanning.